Europhys. Lett.
Volume 67, Number 5, September 2004
Page(s) 773 - 778
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 August 2004
Europhys. Lett., 67 (5), pp. 773-778 (2004)
DOI: 10.1209/epl/i2004-10125-6

Roton and phonon linewidths in superfluid 4He

T. Keller1, 2, K. Habicht3, 4, R. Golub4 and F. Mezei4

1  Max-Planck-Institute for Solid State Research - D-70569 Stuttgart, Germany
2  FRM-2 - D-85747 Garching, Germany
3  TU Darmstadt, Institut für Festkörperphysik - D-64289 Darmstadt, Germany
4  Hahn-Meitner-Institut, BENSC - D-14109 Berlin, Germany

(Received 5 March 2004; accepted in final form 25 June 2004)

We present high-resolution data of the energy widths $\Gamma$ of elementary excitations in superfluid $\chem{{}^{4}He}$ on the phonon branch 0.3Å -1 < Q< 0.6 Å -1 and both the energies and the widths on the roton branch 1.93Å -1<Q<2.6Å -1 at T=0.98 $\un{K}$. In both Q-regions a broadening of $\Gamma$ is clearly observed. The roton energies and group velocities observed in the present experiment are significantly smaller than those reported from previous experiments.

61.12.Ex - Neutron scattering (including small-angle scattering).
67.40.Db - Quantum statistical theory; ground state, elementary excitations.

© EDP Sciences 2004